v4l2-compliance/ctl: drop libv4l2 dependency if NO_LIBV4L2 is defined

v4l2-compliance/ctl: drop libv4l2 dependency if NO_LIBV4L2 is defined

This patch introduces a check for a NO_LIBV4L2 symbol in v4l2-compliance
and v4l2-ctl, which, when defined, will let the utility be built without
linking with libv4l2.

The wrapper functionality libv4l2 provides is obviously lost when
building with NO_LIBV4L2 defined.

Signed-off-by: Hans-Christian Egtvedt <hegtvedt@cisco.com>
[hans.verkuil@cisco.com: modified to reduce number of #ifdefs]
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>